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// 
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// this work for additional information regarding copyright ownership.
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// the License. You may obtain a copy of the License at
// 
// http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
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using System;

using log4net;

namespace log4net.Core
{
    /// <summary>An evaluator that triggers at a threshold level</summary>
    /// <remarks>
    /// <para>
    /// This evaluator will trigger if the level of the event
    /// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
    /// is equal to or greater than the <see cref="Threshold"/>
    /// level.
    /// </para>
    /// </remarks>
    /// <author>Nicko Cadell</author>
    public class LevelEvaluator : ITriggeringEventEvaluator 
    {
        /// <summary>The threshold for triggering</summary>
        private Level m_threshold;

        /// <summary>Create a new evaluator using the <see cref="Level.Off"/> threshold.</summary>
        /// <remarks>
        /// <para>
        /// Create a new evaluator using the <see cref="Level.Off"/> threshold.
        /// </para>
        /// <para>
        /// This evaluator will trigger if the level of the event
        /// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
        /// is equal to or greater than the <see cref="Threshold"/>
        /// level.
        /// </para>
        /// </remarks>
        public LevelEvaluator() : this(Level.Off)
        {
        }

        /// <summary>Create a new evaluator using the specified <see cref="Level"/> threshold.</summary>
        /// <param name="threshold">the threshold to trigger at</param>
        /// <remarks>
        /// <para>
        /// Create a new evaluator using the specified <see cref="Level"/> threshold.
        /// </para>
        /// <para>
        /// This evaluator will trigger if the level of the event
        /// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
        /// is equal to or greater than the <see cref="Threshold"/>
        /// level.
        /// </para>
        /// </remarks>
        public LevelEvaluator(Level threshold)
        {
            if (threshold == null)
            {
                throw new ArgumentNullException("threshold");
            }

            this.m_threshold = threshold;
        }

        /// <summary>the threshold to trigger at</summary>
        /// <value>
        /// The <see cref="Level"/> that will cause this evaluator to trigger
        /// </value>
        /// <remarks>
        /// <para>
        /// This evaluator will trigger if the level of the event
        /// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
        /// is equal to or greater than the <see cref="Threshold"/>
        /// level.
        /// </para>
        /// </remarks>
        public Level Threshold
        {
            get { return this.m_threshold; }
            set { this.m_threshold = value; }
        }

        /// <summary>Is this <paramref name="loggingEvent"/> the triggering event?</summary>
        /// <param name="loggingEvent">The event to check</param>
        /// <returns>This method returns <c>true</c>, if the event level
        /// is equal or higher than the <see cref="Threshold"/>. 
        /// Otherwise it returns <c>false</c></returns>
        /// <remarks>
        /// <para>
        /// This evaluator will trigger if the level of the event
        /// passed to <see cref="M:IsTriggeringEvent(LoggingEvent)"/>
        /// is equal to or greater than the <see cref="Threshold"/>
        /// level.
        /// </para>
        /// </remarks>
        public bool IsTriggeringEvent(LoggingEvent loggingEvent) 
        {
            if (loggingEvent == null)
            {
                throw new ArgumentNullException("loggingEvent");
            }

            return (loggingEvent.Level >= this.m_threshold); 
        }
    }
}
